In color printing, a printer prints input data onto a print medium, such as paper. A CMYK printer, for example, represents bitmap data with various levels of cyan (C), magenta (M), yellow (Y), and black (K) ink. Each of these inks has a unique chemical makeup and fluid content (e.g., carrier fluids including water) that result in differing drying characteristics. In other words, some ink combinations contain more fluid than other ink combinations and therefore require additional drying to attach the ink particles to the print medium.
Printer systems are typically configured with heaters or dryers that are used to evaporate the fluid content of the ink such that the ink attaches to the print medium. In production printing systems, these dryers have multiple elements that radiate heat to a continuous form print medium, or “web”, so as to dry the ink onto the print medium after the print engine applies the ink to the print medium. To accommodate the different drying characteristics of inks, the heating elements are generally configured to radiate a uniform heat that is established based on the area of the substrate that contains the highest concentration of ink. Thus, by ensuring that the highest concentration of ink is dried on the print medium, all inks are virtually assured of being attached to the print medium. Generally, a portion of the radiant heat energy from the print dryer is absorbed into the dryer's structural members and shields. Certain print dryers, such as infrared dryers, also use an exhaust system to remove the evaporated carrier fluid as well as the absorbed heat from the immediate environment.
In any case, the uniform application of heat to the print medium results in the unnecessary consumption of energy since not all applications of ink require the same amount of heat for evaporation of the carrier fluids. This results in more expensive printing operations, particularly in the case of high-speed production printing systems. Moreover, the excessive application of heat to certain parts of the print medium results in a potential fire hazard. For example, areas of the print medium with lower concentrations of ink sometimes dry faster, causing the print medium to be overheated. And, in some instances, paper dust from the print medium propagates through the dryer and catches fire.